1. Industrial Useful Field
This invention relates, for example, to a planetary carrier for a planetary gear transmission employed in an automatic transmission for automobile.
2. Prior Art and its Problem
As shown in FIG. 6, a planetary carrier 100 for conventional Ravineaux type planetary gear transmission, for example, is a solid cast or forged article and connection parts 102 are provided in this planetary carrier 100 at circumferential plural places.
Incidentally, the applicant of this invention has invented a combination of a torque converter having an four-element impeller and a partly improved Ravineaux type planetary gear train, and has applied it for a patent (Japanese Patent Application Ser. No. 60-25906, U.S. patent application Ser. No. 826,039, German Patent Application Ser. No. P 36 04 393 Al).
In this prior art, first and second planetary gears are carried by a planetary carrier and are meshed with separate sun gear (inner peripheral side) and ring gear (outer peripheral side) respectively.
Therefore, when the planetary carrier 100 as shown in FIG. 6 is employed in such a prior art, a diameter of the planetary carrier 100 must be enlarged in order to avoid an interference between the connection parts 102 and the both planetary gears. Consequently, diameters of the sun gear and the ring gear must naturally be enlarged to cause an increase in the overall size of the planetary gear train.